It is known that organic polymers containing at least one reactive silyl group in the molecule have properties such that they are crosslinked under siloxane bond formation resulting from hydrolysis and other reactions of the reactive silyl group due to moisture and the like, even at room temperature to give rubber-like cured products.
Among these reactive silyl group-containing polymers, those polymers which have a polyoxyalkylene type or polyisobutylene type main chain skeleton are disclosed in Patent Document 1, Patent Document 2 and the like and have already been produced industrially and are in wide use in such fields as sealants, adhesives and coatings.
For obtaining cured products from a curable composition including such reactive silyl group-containing organic polymers, a silanol condensation catalyst is used. Generally used as the silanol condensation catalyst are organotin type catalysts having a carbon-tin bond such as dibutyltin bis(acetylacetonate) and dibutyltin dilaurate. In recent years, however, the toxicity of organotin type compounds have been pointed out and development of non-organotin catalysts has been desired.
Patent Document 3, Patent Document 4, Patent Document 5, Patent Document 6 and Patent Document 7 disclose carboxylic acid tin salts and other carboxylic acid metal salts as silanol condensation catalysts. Patent Documents 3 to 7 further disclose that the addition of an amine compound as a promoter to these catalysts results in improved curability. However, from the viewpoint of reduction in environmental stress, substantially metal-free curing catalysts are desired and, Patent Document 8 discloses the combined use of an amine compound and a carboxylic acid for giving a metal-free silanol condensation catalyst.
It is publicly known that the combined use of an amine compound and other silanol condensation catalysts leads to improved curability. However, when the non-organotin type catalysts described in the patents mentioned above are used, there arises a problem such that the adhesiveness of the cured products obtained is inferior as compared with the use of organotin type catalysts.
There are disclosed almost no examples in which amine compounds are used singly as silanol condensation catalysts. Patent Document 9 discloses a technology which comprises utilizing certain amine compounds known in the art as silanol condensation catalysts and mentions 1,8-diazabicylco[5.4.0]undecene-7 (DBU) and the like as the amine compounds
However, when the amine compounds described in Patent Document 9 are used as silanol condensation catalysts of the reactive silyl group-containing organic polymers, some curable compositions exhibit no practical curability. Furthermore, there are certain cases where, although the curable compositions exhibit practical curability, the cured products obtained therefrom are inferior in adhesiveness.
Patent Document 10 discloses a technology which comprises using biguanide compounds, which constitute a group among amine compounds, as silanol condensation catalysts.
However, when the amine compounds described in Patent Document 10 are used as silanol condensation catalysts of the reactive silyl group-containing organic polymers, some curable compositions are inferior in surface curability and depth curability at the early stage of curing.
Patent Document 10 discloses a method in which a biguanide compound (solid at room temperature) is dissolved in a plasticizer or an organic solvent and then added. Upon use of the disclosed plasticizer, there are, however, some cases where amidine compounds are precipitated due to insufficient solubility, or the storage stability of a one-pack type composition is deteriorated due to moisture contained in the plasticizer. There also has been a problem that upon use of the disclosed organic solvent, volatilization of the organic solvent brings about pollution of the work environment.    Patent Document 1: Japanese Kokai Publication S52-73998    Patent Document 2: Japanese Kokai Publication S63-6041    Patent Document 3: Japanese Kokai Publication H05-39428    Patent Document 4: Japanese Kokai Publication H09-12860    Patent Document 5: Japanese Kokai Publication 2000-313814    Patent Document 6: Japanese Kokai Publication 2000-345054    Patent Document 7: Japanese Kokai Publication 2003-206410    Patent Document 8: Japanese Kokai Publication H05-117519    Patent Document 9: WO2004/022618    Patent Document 10: Japanese Kokai Publication 2005-248175